commit "hidpp20: features: add BATTERY_VOLTAGE (0x1001) support" causes error

I narrowed down this error to this commit. Fix following shortly, I hope.

bin/solaar show Unifying Receiver Device path : /dev/hidraw0 USB id : 046d:c52b Serial : 965E9E17 Firmware : 12.10.B0032 Bootloader : 02.14 Other : AA.AA Has 6 paired device(s) out of a maximum of 6. Notifications: wireless, software present (0x000900) Device activity counters: 1=77

1: Wireless Mouse M510 Codename : M510 Kind : mouse Wireless PID : 1025 Protocol : HID++ 1.0 Polling rate : 8 ms (125Hz) Serial number: E7D0A7E1 Firmware: 23.01.B0016 The power switch is located on the base. Notifications: battery status (0x100000). solaar: error: cannot unpack non-iterable NoneType object